Skeletal muscle
A type of muscle that is attached to the skeleton and is under voluntary control.
Smooth muscle
A type of muscle found in the walls of organs, such as the stomach, and is responsible for involuntary movements.
Cardiac muscle
A type of muscle found in the walls of the heart and is responsible for involuntary contractions.
Striation
The visible arrangement of actin and myosin myofilaments in muscle fibers.
Voluntary control
The ability to consciously control the contraction and relaxation of skeletal muscles.
Involuntary
Not under conscious control, such as the contraction of smooth and cardiac muscles.
Fibers
The elongated cells that make up muscle tissue.
Irritability
The ability of a muscle to respond to a stimulus.
Contractibility
The ability of a muscle to shorten in length.
Elasticity
The ability of a muscle to stretch and return to its normal position.
Extensibility
The ability of a muscle to extend in length.
Conductivity
The ability of a muscle to transmit nerve impulses.
Origin
The point where a muscle attaches to the more stationary bone of the axial skeleton.
Insertion
The point where a muscle attaches to the bone that is moved.
Action of Muscles
The main function or movement produced by a muscle.
Direction of the fibers
The orientation or alignment of muscle fibers, such as transversus or rectus.
Location of muscles
The position or placement of a muscle in the body, such as anterior or posterior.
Number of divisions/heads
Some muscles have multiple origins or layers, indicated by prefixes like "bi" or "tri."
Shape of the muscle
The appearance or form of a muscle, such as deltoid or trapezius.
Muscle's points of attachment
The bones or specific spots on bones to which a muscle attaches.
Agonist
The muscle primarily responsible for movement of a body part.
Antagonist
The muscle that counteracts the agonist, lengthening when the agonist contracts.
Concentric contraction
Muscle fibers shorten during contraction.
Isometric contraction
Muscle fibers do not change in length during contraction. (same length)
Isotonic exercise
Controlled shortening and lengthening of the muscle, using dumbbells or barbells.(same tension)
Isometric exercise
Muscles maintain a constant length, often using an immovable surface or object.(same length)
Isokinetic exercise
Involves machines that control the speed of contraction, combining features of isotonic and isometric exercises.
Hypertrophy
Increased size and muscularity of muscles due to increased mitochondrial density, capillary density, and muscle protein levels.
Motor unit recruitment
Increased activation of motor units, resulting in increased strength.
Connective tissue
The tissue that supports and connects muscles, becoming stronger with resistance training.
Sarcomere
The basic structural unit of a muscle fiber, consisting of overlapping thick and thin filaments.
Sarcolemma
The cell membrane of skeletal muscle fibers.
Mitochondrion
An organelle responsible for producing energy in the form of ATP in muscle cells.
Myofibril
A thread-like structure within muscle fibers that contains the contractile proteins actin and myosin.
Dark and Light Bands
Alternating bands within a sarcomere that give skeletal muscle its striated appearance.
Nucleus
The central part of a cell that contains genetic material and controls cellular functions.
Thick Filaments
Bundles of myosin protein within a sarcomere that interact with thin filaments during muscle contraction.
Thin Filaments
Made up of actin protein, these filaments slide past thick filaments during muscle contraction.
Z Disc
A protein structure that anchors the thin filaments and separates one sarcomere from the next.
H Zone
The region within a sarcomere where only thick filaments are present.
A Band
The region within a sarcomere where thick filaments are present, including the H zone and the zone of overlap with thin filaments.
I Band
The region within a sarcomere where only thin filaments are present.
Neuromuscular System
The combination of the nervous system and muscular system that allows for control and movement of skeletal muscles.
Neuromuscular Junction
The point where a motor neuron meets a muscle fiber, allowing for communication between the nervous system and muscular system.
Transverse Tubule (T-Tubule)
Invaginations of the sarcolemma that help stimulate and coordinate muscle contractions.
Sarcoplasmic Reticulum
A membrane network within muscle cells that plays an essential role in controlling and contraction of individual myofibrils.
Z Line
Located at each end of a sarcomere, the point at which the thin filaments attach.
Zone of Overlap
The area within a sarcomere where both thin and thick filaments are present.
Neuromuscular Junction
The point where a motor neuron meets a muscle fiber, allowing for communication between the nervous system and muscular system.
Action Potential
A rapid change in electrical potential across the membrane of a muscle cell, leading to muscle contraction.
Vesicles
Small sacs within the synaptic knob that contain neurotransmitters.
Acetylcholine (ACh)
A neurotransmitter that plays a key role in muscle contraction.
Motor End Plate
The region of the muscle fiber membrane that contains receptors for acetylcholine.
Calcium (Ca2+)
An ion that plays a crucial role in muscle contraction by triggering the release of neurotransmitters and allowing for the interaction between actin and myosin.
Troponin
A protein that binds to calcium ions and regulates the interaction between actin and myosin during muscle contraction.
Tropomyosin
A protein that covers the active sites on actin and prevents interaction with myosin in the absence of calcium.